This invention relates to targeting apparatus for use in resectioning a femur when performing transfemoral osteotomy. In this surgical technique the femur is exposed along a proximal/distal line, the soft tissue (skin, muscle) being folded back on each side to expose the bone. The proximal end of the femur is now open as a xe2x80x9cwindowxe2x80x9d and a femoral prosthesis is inserted into the bone canal.
The technique requires careful pre-operative planning, usually from X-rays, and it is possible to calculate in advance how far to cut the xe2x80x9cwindowxe2x80x9d so that the distal edge of the xe2x80x9cwindowxe2x80x9d end can become a datum base.
There are difficulties and disadvantages when using this technique due to the possibilities of damaging the soft tissue when resectioning the bone. The soft tissue has to be opened along a proximal/distal line and the bone then cut along the same line. This is usually done with a saw but it will be appreciated that the cutting of the soft tissues above the saw cut necessary destroys the tissues in the area. When the further two cuts along a proximal/distal line are made in order to allow the two pieces of cut bone to be opened out form the xe2x80x9cwindowxe2x80x9d there is again severe damage to the soft tissue and this can severely effect the healing process when the window is subsequently closed.
The present invention is intended to provide instrumentation which can be employed with a technique which will not only avoid damage to the soft tissue but enable the xe2x80x9cwindowxe2x80x9d to be more easily closed.
The apparatus according to the invention can also be used with apparatus for performing the remainder of the transfemoral osteotomy.
There are obvious difficulties in assessing the particular angular position of the prosthesis in the femoral canal and the exact location of the resectioning of the femur must be accurately judged. A further difficulty arises with regard to the placement of one or more retaining bolts towards the distal end of the stem of the prosthesis. These bolts, screws or pins pass through the bone, the stem of the prosthesis and out through the other side of the bone thus anchoring the prosthesis in position. It is difficult for surgeons to judge the exact position to drill the holes in the bone to coincide with the holes in the implant and it is also necessary to select the correct angular position for the prosthesis and therefore the holes. It is also difficult to judge the exact distance down the femur for the holes to achieve the correct leg length of the correction.
This apparatus for use in performing transfemoral osteotomy is intended to overcome some of the difficulties referred to above and the present apparatus can be used in conjunction with it.
According to the present invention a targeting apparatus for use in resectioning a femur when performing transfemoral osteotomy surgery comprises a drill guide element which includes a line of drill opening each of which is adapted to guide a drill and a connector or clamp for rigidly securing the drill guide element to a femur to be resectioned with the line of openings extending in a proximal/distal direction.
The apparatus can be used by securing the drill guide element to the femur and drilling through the line of openings to provide an interrupted cut along the bone. Because the drill passes through the soft tissue it is not completely cut but merely has a series of perforations along its length. Prior to drilling the line of holes in the bone the first proximal/distal saw cut will have been made along the top and the longitudinally extending portion of bone can now be broken away along the line of drill holes. The soft tissue is however still in existence between the remainder of the femur and the separated portion so that it can hold the folded back separated portion in place alongside the remainder of the femur and it also provides anchorage when the window is closed. The same technique is used on the other side of the femur so that a completely open window exposing the femoral canal is produced.
It will be appreciated that the first cut to be made is the transverse cut which provides an exposed end from which the xe2x80x9cwindowxe2x80x9d extends in a proximal direction.
Preferably an adjuster is included for altering the angular position of the drill guide element on the femur about a proximal distal axis after it has been secured thereto thus enabling accurate placement of the holes. In order that both sides of the opening can be drilled without readjustment of the apparatus the drill guide element can include two parallel lines of drill openings.
Adjacent drill openings can be angled in relation to each other so that the openings are more clearly spaced apart on the outer side of the element than on the inner side adjacent the femur and preferably each of the entry points of the openings on the outer side of the element serves two or more openings so that there are more entry points for openings on the inner side of the element than on the outer side. This enables a row of closely spaced openings to be drilled on each side.
The drill guide element can also include a guide for guiding a device for exposing the femur along a proximal distal line. This can be in the form of a guide slot through which the surgeon can open the soft tissue and subsequently saw the first longitudinally extending cut in the bone after it has previously been cut transversely.
The drill guide element may conveniently be removably connected to the connector which secures the drill guide to the femur to assist in sterilization and so that the connector can be used in other apparatus.
Preferably the connector for securing the element to the femur is in the form of an adjustable open jawed clamp adapted to partially surround the femur with which it is to be used.
A locator can also be included for locating the connector on a partially resectioned transverse end of the femur after the first transverse cut has been made.
Because of the particular design of the connector or clamp it can also be used in other apparatus for use in performing transfemoral osteotomy.
If the drill guide element is removed from the means for securing it to the femur the securing element can be attached to apparatus as set out in the applicant""s co-pending U.S. applications, Ser. Nos. 10/008,336 and 10/011,047 filed on the same day of the present application, claiming priority of British Patent Application Nos. GB-A-00 27698.0 and GB-A-01 05779.3.
The present invention therefore also includes targeting apparatus for use in performing transfemoral osteotomy surgery as set forth above which also includes a support element provided with a drill guide, a connector or clamp for securing the support element to a resectioned femur, a connector for connecting the drill guide element to the support element, and an adjuster for adjusting the angular position of the drill guide in relation to the resectioned femur about a proximal/distal axis in relation to the resectioned femur about a proximal/distal direction.
With this arrangement the connector acts to secure a support element provided with a drill guide to a prosthesis to be implanted and to a resectioned femur, and an adjuster for adjusting the angular position of the drill guide in relation to the resectioned femur about a proximal distal axis.
Thus, this apparatus which incorporates the connector or clamp set forth above can be used to accurately locate the angular position of the drill guide on the prosthesis (anteversion setting) which can be used to drill the holes to take the retaining bolt or bolts in the bone. Preferably the support element includes a connector for connection to the proximal end of the femoral prosthesis and an indicator can be provided to indicate the angular position of the drill guide relative to the resectioned femur.
Thus, after careful X-ray examination, the precise anteversion setting can be decided and this can then be transferred to the apparatus thus ensuring the correct angular position.
This apparatus can also include an adjuster for adjusting the support element to accommodate alternative leg lengths. In order to do this a device can be included to vary the proximal/distal position of the support element in relation to the prosthesis securing means.
The support element is preferably in the form of an L-shaped frame one arm of which carries the drill guide and the femur securing connector and the other arm carrying the connector for connection to the femoral prosthesis which is to be implanted.
With this arrangement the femur clamp or connector which has already been used in opening the xe2x80x9cwindowxe2x80x9d can be connected to the L-shaped frame by a bracket which should be adjusted in proximal/distal directions on the frame and in relation to which the connector or clamp can be angularly adjusted about a proximal/distal axis.